A childhood belief about classes

The lady who babysat me as a kid had three older kids of her own. I remember her once asking her daughter what she had learned in school that day. The daughter replied, "I learned that X equals 7!" I became convinced then, that all letters corresponded with numbers and this was something you had to memorize when you were in the higher grades. I spent the rest of the day wondering what number "A" was.

Funny thing is, I told my husband about this and he had a very similar experience after asking someone what "Algebra" was!